Named after its hook-like horns, cat's claw (Uncaria tomentosa) is a woody vine native to the Amazon rainforest and other places in South and Central America. The bark and root have been used by South Americans for centuries to treat health problems including arthritis, stomach ulcers, inflammation, dysentery, and fevers. It was also used as a form of birth control.

Test tube studies indicate that cat's claw may stimulate the immune system, help relax the smooth muscles (such as the intestines), dilate blood vessels (helping lower blood pressure), and act as a diuretic (helping the body eliminate excess water).

Cat's claw also has antioxidant properties, helping the body eliminate particles known as free radicals that damage cells. Scientists believe free radicals to contribute to health problems, including heart disease and cancer. Antioxidants can help neutralize free radicals and may reduce, or even help prevent, some of the damage they cause.

Some early studies suggest cat's claw may kill tumor and cancer cells in test tubes.

Osteoarthritis

Not many scientific studies have looked at the safety and effectiveness of cat's claw, but it has been used traditionally to treat osteoarthritis (OA). One study found that it may help relieve pain from knee OA without significant side effects.

Rheumatoid arthritis

Cat's claw has been suggested as a treatment for rheumatoid arthritis (RA) because it may help reduce inflammation. One small study of people who were already taking sulfasalazine or hydroxychloroquine to treat RA found that those who also took cat's claw had fewer painful, swollen joints than those who took a placebo (dummy pill). But although cat's claw may help reduce inflammation, there is no evidence to show that it stops joint damage from getting worse. For that reason, RA should be treated with conventional medications, which can stop joint damage.

Further research

Cat's claw is being studied for a number of other possible uses, including HIV, Crohn disease, multiple sclerosis, systemic lupus erythematosus (SLE or lupus), endometriosis, kidney problems, bladder cancer, and Alzheimer disease. More research is needed before scientists can say whether it is effective.

Cat's claw is a thorny vine that can climb as high as 100 feet. It grows mostly in the Amazon rainforest, as well as tropical areas in South and Central America. Much of the cat's claw sold in the United States was grown in Peru.

Cat's claw got its name from the curved, claw-like thorns that grow on its stem. The root and bark of cat's claw are the parts used for medicine.

Cat's claw contains many types of plant chemicals that help reduce inflammation, such as tannins and sterols, and fight viruses, such as quinovic acid glycosides.

Cat's claw preparations are made from the root and bark of the cat's claw vine. How effective the root and bark are may depend on what time of year the plant was harvested.

The bark of the cat's claw vine can be crushed and used to make tea. Standardized root and bark extracts (containing 3% alkaloids and 15% phenols) are also available in either liquid or capsule forms.

Pediatric

No one has studied cat's claw in children, so no one knows whether it is safe. DO NOT give a child cat's claw except under your doctor's supervision.

Adult

Speak to your health care provider regarding dosing instructions.

The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, can trigger side effects, and can interact with other herbs, supplements, or medications. For these reasons, you should take herbs with care, under the supervision of a health care provider.

Cat's claw appears to have few side effects, however, there have not been enough scientific studies on cat's claw to determine its safety. Some people have reported dizziness, nausea, and diarrhea when taking cat's claw. The diarrhea or loose stools tend to be mild and go away with continued use of the herb.

Pregnant or nursing women should not take cat's claw because it may cause miscarriage.

People with autoimmune diseases, skin grafts, tuberculosis, or those receiving organ transplants should not use cat's claw unless specifically directed by their physician because of its possible effects on the immune system.

People with leukemia or low blood pressure should not take cat's claw.

People with kidney or liver disease should not use cat's claw without first asking their doctor.

If you are currently taking any of the following medications, you should not use cat's claw without first talking to your health care provider.

Medications that suppress the immune system: In theory, because cat's claw may stimulate the immune system, it should not be used with medications that suppress the immune system. Those include cyclosporine or other medications prescribed following an organ transplant, or to treat an autoimmune disease.

Blood-thinning medications: Cat's claw may increase the risk of bleeding, especially if you also take blood thinners such as aspirin, warfarin (Coumadin), or clopidogrel (Plavix).

Diuretics (water pills): Cat's claw may act as a diuretic, helping the body eliminate excess fluid. If you also take diuretics, which do the same thing, you could be at risk of developing an electrolyte imbalance.

Blood pressure medication: Cat's claw may lower blood pressure. If you take medication for high blood pressure, taking cat's claw may cause your blood pressure to be too low.

Other medications: Cat's claw may interfere with some medications that are processed by the liver. If you take any medications, check with your doctor before taking cat's claw.

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